A variable valve mechanism 90 according to the related art illustrated in FIG. 10 is described in Patent Document 1. The variable valve mechanism 90 includes a rocker arm 93 swingably placed on a support member 92 that projects upward. The rocker arm 93 includes an input member 93A driven by cams 91 and 91 (high-lift cams) and an output member 93B that drives a valve 7.
The variable valve mechanism 90 further includes switching pins 96 and 96 and a hydraulic chamber 98 provided inside the rocker arm 93, and an oil passage 97 that extends to the hydraulic chamber 98 by way of the support member 92 and the rocker arm 93. The variable valve mechanism 90 switches the drive state of the valve 7 by displacing the switching pins 96 and 96 between a coupling position at which the switching pins 96 and 96 extend between the input member 93A and the output member 93B and a non-coupling position at which the switching pins 96 and 96 do not extend between the input member 93A and the output member 93B based on variations in hydraulic pressure in the oil passage 97 and the hydraulic chamber 98. The variable valve mechanism 90 further includes lost motion springs 95 and 95 that urge the input member 93A toward the cams 91 and 91 at a non-coupled time.